GETTYSBURG — There was no shortage of re-enactors at Gettysburg’s 150th anniversary battle portrayal this year. More than 10,000 signed up to parade around in wool garb, toting muskets and pushing cannons underneath a relentless summer sun.

But for many, this year will be their last battle. And as the sun sets on Gettysburg’s sesquicentennial, some wonder what will happen to their aging living-history hobby when they are gone.

A wooded area near the annual Gettysburg Anniversary Committee re-enactment “battlefield” provides respite from the July sun. At the Union hospital tent sits Pete Peters, known simply as “Doc” to the soldiers he treats. Peters has been re- enacting for 50 years.

He is a grizzled veteran of a graying hobby. While the average age of a Union soldier in the 1860s was younger than 26, most estimates put the average age of a 2013 re-enactor around 40.

“Re-enacting’s changed,” said the 75-year-old Peters, a retired assistant chief for a volunteer fire department in Whitehall. “You’re not getting kids involved anymore.”

Peters plans to make the Civil War sesquicentennial his final campaign.

“It gets harder and harder every year,” Peters said. “I won’t make the 175th or the 200th.”

Primed to turn 80 in August, Bob Packard, of Lenhartsville, serves as an ordnance sergeant and Peters’ chief aide. He picked up the hobby when he was 68.

How much longer does he intend to re-enact? “Not too long more,” Packard said.

Peters would like to go to Appomattox Court House in Virginia in 2015 to honor the sesquicentennial of General Robert E. Lee’s surrender and the end of the Civil War.

“That would be the end of the sesquicentennials,” Peters said. “Then I’m gonna hang up my scalpels, saws and knives and retire from it. If I make it that long.”

Five decades ago, when Peters started re-enacting, the hobby was just beginning to pick up. At Gettysburg in July 1963, he and two buddies — now deceased — re-enacted in simple blue clothes. Authentic reproduction of uniforms or accoutrements did not take hold until around the 125th anniversary, Peters said.

Jonathan Quigley, a 26-year-old from Hedgesville, W.Va., who has been out of the hobby for a while, said there has been a split among re-enactors. Some people re-enact as a hobby, he said, while others are strong advocates of historical authenticity.

“There will always be hardcore re-enactors because they want to be accurate and do it like the soldiers in the Civil War,” he said. “There will also always be those that like to sit on coolers and drink out of Coke cans while they text on their cellphones.”

Andrea DiMartino, media relations coordinator for the Gettysburg Anniversary Committee, said that when the movie “Gettysburg” came out in 1993, there was a strong resurgence of interest in re-enacting.

“It looks like it’s still growing,” she said. “But a lot of older guys are saying this will be it for them.”

At the same time, some younger re-enactors say they have trouble finding the time for their hobby.

Adam Stoner, 22, started re-enacting 10 years ago, and he said he’s seen the hobby shrink as those around him age. But he believes history moves in cycles.

“We’re not really bringing in youngsters,” he said. “But in 50 years, it will probably look the same as it does now. When we hit the 25- and 50-year anniversaries, it picks up. But then it dwindles down a bit.”

And when interest surges, there will certainly be a committed cadre of younger soldiers, those who grew up in families for whom living-history campaigns are a way of life.

“I was always a huge history guy,” Jeffrey said. “I’ve seen all the Gettysburg movies hundreds of times.”

When he was a boy, Jeffrey and other children of re-enacting parents would stage their own battles, shooting cap guns at one another behind hay bales while their parents did living-history demonstrations.

“It was nice to see a bunch of 7-year-olds say, ‘I can’t wait to have a real gun,’” his aunt, Julie Baldwin said. “It was cool to see kids want to participate.”

Like his sister, Jeffrey Hulse is not ready to admit the hobby’s defeat.

“It’s up to these older guys to get the kids interested,” Jeffrey said. “Kids that are into history should get a chance to keep this alive.”

Re-enactor Josh Withrow, 27, said he has seen declining numbers of re-enactors through the years but figures there will always be an appeal for a re-enactment at Gettysburg.

“If you’re enough of a history buff, just reading about it will never be enough,” he said.

But when he said he wants to re-enact for as long as he can, 59-year-old Gib Buckbee, a fellow re-enactor, felt the need to interject a little reality.